Astro::Aladin module
--------------------  

What is it?
-----------

The module is an object orientated interface into the resources provided
by the CDS Aladin project

What is CDS Aladin?
-------------------

Aladin is an interactive software sky atlas allowing the user to visualize 
digitized images of any part of the sky, to superimpose entries from 
astronomical catalogues or databases, and to interactively access related 
data and information from the Simbad database and the VizieR service and 
other archives for all known objects in the field. The driving motivation 
behind Aladin is the desire to provide a visual summary of the multi-wavelength
sky. It is particularly useful for multi-spectral cross-identifications of
astronomical sources, observation preparation and quality control of new 
data sets (by comparison with standard catalogues covering the same region 
of sky). Aladin is developed and maintained by the Centre de Donnees
astronomiques de Strasbourg (CDS). The Aladin project manager is Francois
Bonnarel <bonnarel@astro.u-strasbg.fr>

See http://aladin.u-strasbg.fr/aladin.gml for more information about the
Aladin Project.

How are we accessing the resources?
-----------------------------------

The CDS Aladin Java Tool is driven in script mode using an anonymous pipe
from the low level module Astro::Aladin::LowLevel. High level access to
data is provided by the Astro::Aladin module itself. It's not advisable
to use the low level module directly unles you're sure you know what
your doing.

What is the Aladin Java Tool?
-----------------------------

The Aladin java tool is the user interface of the CDS Aladin Project. It 
allows the user to query images, catalogues, data, to manipulate the images 
by zooming or modifying the dynamics, to access the full records of any 
sources, to add symbols, vectors, etc.

Aladin interface has been developed and is maintained by Pierre Fernique
<fernique@astro.u-strasbg.fr> (CDS).

Why do it?
----------

Or rather, why do it this way? The Aladin project gives you access
to a whole bunch of different surveys and catalogues, but unfortunately 
the Aladin Application is shipped as a JAR file, without source. 

I needed to access these resources quickly from Perl, so the easiest,
way seemed to be to drive the Aladin application in script mode using
its command line interface.

This is not an optimal solution, its not even a sub-optimal solution,
it's a kludgy hack. On the other hand it does seem to work, and the
worst of it is heavily disgused by the high level convience routines
in Astro::Aladin.

If I'd had the source code I would have wrapped the Java source using
Inline::Java which would have been alot neater. Better yet if I'd
had the API for the  backend databases I could have written a Perl
native implementation (although this would have taken alot longer).

Unfortunately we're currently stuck with the kludge.

Requirements
------------

The module need a locally installed version of the CDS Aladin Java 
Standalone application. Aladin works on Windows, MacOS, MacOS X, AIX,
Solaris, Linus, HP-uX and virtually any other platform that has
a JDK available.

See http://aladin.u-strasbg.fr/java/Aladin_Web_Installers/install.htm
for download details.

After installation you should set the ALADIN_JAR environment varible
to point to the Aladin.jar file. This will be picked up by the module
and used to locate your Aladin installation.

You should also set the ALADIN_MEM variable, which defaults to "128m"
which gives 128Mb of memory to the JVM. For large catalogue retrivals,
with radii in excess of 15 to 20 arcminutes, this should be significantly
increased.

Provides
--------

The package provides the following classes

    Astro::Aladin
    Astro::Aladin::LowLevel

further information can be found in the POD included in Aladin.pm

Where can I get it?
-------------------

The package is availabe from CPAN <http://www.cpan.org/> and from
the eSTAR Project at http://www.estar.org.uk/

Installation
------------

Installation is automated using the ExtUtils::MakeMaker library

     % perl Makefile.PL
     % make
     % make test
     % make install

Authors
-------

The module was written by Alasdair Allan <aa@astro.ex.ac.uk>, of the 
University of Exeter Astrophysics Group (http://www.astro.ex.ac.uk/) 
as part of his work for the eSTAR project.

License
-------
This package is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place,Suite 330, Boston, MA  02111-1307, USA
